1. Field of the Invention
The present invention generally relates to an image-reading device, an image-forming device, and a copying machine, and more particularly, to an image-reading device which exposes and scans an image of a subject copy by moving two travelers including an exposure lamp and mirrors at different velocities.
2. Description of the Related Art
Conventionally, there has been an image-reading device that exposes and scans an image of a subject copy placed on a contact glass by causing a stepping motor to drive a first traveler including an exposure lamp and a mirror, and a second traveler including two mirrors, along a sub (slow) scanning direction at a velocity ratio of 2:1.
Generally, in the image-reading device that causes the stepping motor to drive the first traveler and the second traveler, a driving velocity of the stepping motor is controlled to change gradually, because of structural requirements. Additionally, another type of image-reading device causing the stepping motor to drive the first traveler and the second traveler reads an image of a subject copy within a range where the driving velocity of the stepping motor is constant, because of an easier control required therefor and a quality of the read image achieved therefrom.
Such an image-reading device as mentioned above requires a dimension in the sub scanning direction to be equal to or larger than a total dimension of a dimension in the sub scanning direction of an image of a subject copy and a dimension in the sub scanning direction required for a run-up and a slowdown of the first traveler and the second traveler. In other words, the dimension of the image-reading device in the sub scanning direction can be theoretically decreased to equal the above-mentioned total dimension.
Additionally, for the purpose of miniaturization, there is still another image-reading device in which the first traveler and the second traveler are arranged close to each other in the course of traveling, or are arranged close to each other by being overlapped at a home position.
By the way, the above-mentioned exposure lamp is provided with a lamp harness used for supplying power to the exposure lamp. This lamp harness is connected to one end of a flexible cable the other end of which is connected to a power source. In some image-reading devices, this flexible cable is drawn around a travel-back side of the second traveler (i.e., a side toward which the second traveler travels back), because it becomes easy to assemble the image-reading device, or it becomes easy to draw around the flexible cable.
For the purpose of miniaturizing the image-reading device, it is preferred that the flexible cable be drawn around the travel-back side of the second traveler as closely as possible. However, when the flexible cable is positioned close directly to the second traveler, the flexible cable contacts the mirrors and other elements mounted on the second traveler. Moving the first traveler and the second traveler back and forth repeatedly with the flexible cable contacting the mirrors and other elements mounted on the second traveler may possibly cause the flexible cable and the mirrors to rub on each other so that a friction thereof damages the flexible cable.
To prevent this damage, a conventional image-reading device comprises a cable guide mounted on the second traveler such that a guide surface guiding the flexible cable is positioned between the mirrors and the flexible cable. This arrangement prevents the flexible cable and the mirrors from rubbing on each other, and thus prevents the flexible cable from being damaged therefrom. The cable guide is provided with guide ribs raised from both sides of the guide surface past the flexible cable. These guide ribs position the flexible cable on the guide surface, and prevent the flexible cable from shifting with respect to the guide surface.
By the way, in some cases, the lamp harness is connected to the flexible cable in a state where the lamp harness is deformed toward the second traveler due to a varying precision in assembling the image-reading device.
In the above-described image-reading device including the first traveler and the second traveler arranged close to each other for the purpose of miniaturization, when the first traveler and the second traveler are moved back and forth in the above-mentioned state where the lamp harness is deformed toward the second traveler, the lamp harness is more likely to contact the second traveler or the mirrors mounted on the second traveler. Since the first traveler and the second traveler are reciprocated at different velocities, moving the first traveler and the second traveler back and forth repeatedly may cause the lamp harness to be rubbed by the second traveler or the mirrors mounted on the second traveler, which may result in a fatigue breakage of the lamp harness.
Also, in the above-described image-reading device comprising the cable guide, the guide ribs are raised from both sides of the guide surface past the flexible cable. Therefore, when the first traveler and the second traveler are arranged close to each other for the purpose of miniaturization, the lamp harness deformed toward the second traveler is more likely to contact the guide ribs. Moving the first traveler and the second traveler back and forth repeatedly with the lamp harness contacting the guide ribs may result in a fatigue breakage of the lamp harness.
The fatigue breakage of the lamp harness results in a heteropolar leak involving a voltage difference between the damaged lamp harness and the flexible cable.
As a conceivable countermeasure thereagainst, the assembly of the image-reading device may be performed so that the lamp harness be provided at a prescribed position in consideration of various factors, such as a particular tendency of the lamp harness for bending. However, assembling the image-reading device in consideration of the various bending tendency of the lamp harness takes time so as to reduce a productivity of the assembly, which does not suit a mass production of the image-reading device.
It is a general object of the present invention to provide an improved and useful image-reading device and a copying machine in which the above-mentioned problems are eliminated.
A more specific object of the present invention is to provide an image-reading device, and a copying machine using the image-reading device which can be miniaturized by having a first traveler and a second traveler arranged close to each other without damaging a harness, regardless of a varying precision in an assembly thereof.
In order to achieve the above-mentioned objects, there is provided according to one aspect of the present invention an image-reading device exposing and scanning an image of a subject copy by reciprocating a first traveler including an exposure lamp and a mirror, and a second traveler including two mirrors, along a sub scanning direction at a velocity ratio of 2:1, the image-reading device comprising a harness supplying power to the exposure lamp, a flexible cable having one end connected to the harness and the other end connected to a power source, and a contact prevention member provided on the first traveler so as to prevent the harness from contacting the second traveler and the mirrors included in the second traveler.
According to the present invention, the contact prevention member prevents the harness from contacting the second traveler and the mirrors included in the second traveler. Accordingly, for example, when the first traveler and the second traveler are arranged close to each other for the purpose of miniaturizing the image-reading device, the harness can be prevented from rubbing on the second traveler and the mirrors included in the second traveler and thus from being damaged thereby which would otherwise occur due to a difference between the velocities of the first traveler and the second traveler traveling back and forth. In addition, since the contact prevention member is provided on the first traveler, the contact prevention member moves together with the harness in the course of exposing and scanning an image of a subject copy. Thereby, the harness and the contact prevention member can be prevented from rubbing on each other.
Additionally, the image-reading device according to the present invention may further comprise a cable guide provided on the second traveler so as to guide the flexible cable to a side toward which the second traveler travels back, wherein the contact prevention member prevents the harness from contacting the cable guide.
According to the present invention, the contact prevention member prevents the harness from contacting the cable guide. Accordingly, when the cable guide is provided on the second traveler so as to draw the flexible cable closely around the second traveler, the harness can be prevented from rubbing on the cable guide and thus from being damaged thereby which would otherwise occur due to the difference between the velocities of the first traveler and the second traveler traveling back and forth.
Additionally, the image-reading device according to the present invention may further comprise a plate-form reinforcing member bonded to the flexible cable so that the harness and the flexible cable are connected to each other with the reinforcing member therebetween, wherein the contact prevention member is a plate-form member formed unitarily with the reinforcing member.
At this point, upon soldering wires, a reinforcing plate, for example, may sometimes be used to flatten a part at which the wires are connected, and to flatten a periphery thereof. Thus, when the harness and the flexible cable are connected by soldering, the plate-form reinforcing member according to the present invention becomes necessary for flattening a part at which the harness and the flexible cable are connected, and for flattening a periphery thereof. Additionally, the contact prevention member is provided as a plate-form member formed unitarily with the plate-form reinforcing member so as to reduce the number of elements composing the image-reading device and to decrease the number of steps required for assembling the image-reading device.
Additionally, the image-reading device according to the present invention may further comprise a first connector provided at an end of the harness, and a second connector provided at the one end of the flexible cable so that the first connector is detachably inserted into the second connector, wherein the first connector can be inserted into and detached from the second connector at a side of the second connector opposite the one end of the flexible cable.
According to the present invention, the harness and the flexible cable are led out in an identical direction from a position at which the first connector is inserted into the second connector. Therefore, when the above-mentioned one end of the flexible cable is positioned nearer to the exposure lamp, connecting the harness to the flexible cable by inserting the first connector into the second connector enables the flexible cable to be drawn from the position nearer to the exposure lamp around the second traveler. Accordingly, the first traveler and the second traveler can be arranged closer to each other so as to further miniaturize the image-reading device.
Additionally, in the image-reading device according to the present invention, at least a part of the harness may be fixed to the contact prevention member.
According to the present invention, the harness can be positioned at a periphery of the contact prevention member. Thereby, the harness can be prevented from departing from the contact prevention member into a friction against neighboring elements; thus, the harness can be prevented from being damaged.
Additionally, the image-reading device according to the present invention may further comprise a restricting member provided on a surface of the contact prevention member opposite the flexible cable so as to restrict the harness on the surface of the contact prevention member.
According to the present invention, the harness is restricted to the contact prevention member by the restricting member such that the harness is positioned opposite the flexible cable with the contact prevention member therebetween. Thereby, the harness and the flexible cable can be surely prevented from contacting each other.
In order to achieve the above-mentioned objects, there is also provided according to another aspect of the present invention a copying machine comprising the above-mentioned image-reading device, and an image-forming device forming the image of the subject copy read by the image-reading device on a sheet.
According to the present invention, the copying machine can provide the same advantages as the above-mentioned image-reading device.
Other objects, features and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings.